[PATCH] Add a new kdump.conf option: compress_args - kexec - Fedora mailing-lists

10 May 2021

Allow user to tune between a better compression ratio or better initramfs
build speed. And provide two example for user to use.
If compress_args is not set, then try to use the compression arguments
with highest compression ratio.
Test result with given examples:
- With `compress_args xz -Xbcj x86 -Xdict-size 100%`
 # time kdumpctl rebuild
 kdump: Rebuilding /boot/initramfs-4.18.0-287.el8.dt4.x86_64kdump.img
real    0m29.896s
 user    0m37.784s
 sys     0m5.725s
Image size:
 16441344 May  9 07:44 squash-root.img
- With `compress_args gzip -Xcompression-level 1`
 # time kdumpctl rebuild
 kdump: Rebuilding /boot/initramfs-4.18.0-287.el8.dt4.x86_64kdump.img
real    0m9.098s
 user    0m4.373s
 sys     0m4.508s
Image size:
 21757952 May  9 07:45 squash-root.img
Signed-off-by: Kairui Song kasong@redhat.com
---
 kdump.conf | 13 +++++++++++++
 kdumpctl   |  2 +-
 mkdumprd   | 29 +++++++++++++++++++++++++++++
 3 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/kdump.conf b/kdump.conf
index dea2e94..d86bc44 100644
--- a/kdump.conf
+++ b/kdump.conf
@@ -159,6 +159,18 @@
 #           - List of cluster node(s) except localhost, separated by spaces,
 #             to send fence_kdump notifications to.
 #             (this option is mandatory to enable fence_kdump).
+# compress_args <compressor and args>
+#           - How the kdump initramfs should be compressed.
+#             Kdump compresses the initramfs into a squash image to same
+#             crashkernel runtime memory. More effective compression will
+#             save more memory but make initramfs compression slower.
+#
+#             If not set, kdump will prefer to trade initramfs build time for a
+#             higher compression ratio.
+#
+#             Some example args:
+#             - For better compression ratio (on x86): "xz -Xbcj x86 -Xdict-size 100%"
+#             - For faster initramfs building: "gzip -Xcompression-level 1"
 #
#raw /dev/vg/lv_kdump
@@ -183,3 +195,4 @@ core_collector makedumpfile -l --message-level 7 -d 31
 #dracut_args --omit-drivers "cfg80211 snd" --add-drivers "ext2 ext3"
 #fence_kdump_args -p 7410 -f auto -c 0 -i 10
 #fence_kdump_nodes node1 node2
+#compress_args xz
diff --git a/kdumpctl b/kdumpctl
index 009d259..15dbfbe 100755
--- a/kdumpctl
+++ b/kdumpctl
@@ -257,7 +257,7 @@ check_config()
    	ext[234]|minix|btrfs|xfs|nfs|ssh)
    		config_opt=_target
    		;;
-		sshkey|path|core_collector|kdump_post|kdump_pre|extra_bins|extra_modules|failure_action|default|final_action|force_rebuild|force_no_rebuild|fence_kdump_args|fence_kdump_nodes)
+		sshkey|path|core_collector|kdump_post|kdump_pre|extra_bins|extra_modules|failure_action|default|final_action|force_rebuild|force_no_rebuild|fence_kdump_args|fence_kdump_nodes|compress_args)
    		;;
    	net|options|link_delay|disk_timeout|debug_mem_level|blacklist)
    		derror "Deprecated kdump config option: $config_opt. Refer to kdump.conf manpage for alternatives."
diff --git a/mkdumprd b/mkdumprd
index 50ebdc8..54c8eef 100644
--- a/mkdumprd
+++ b/mkdumprd
@@ -30,6 +30,7 @@ OVERRIDE_RESETTABLE=0
extra_modules=""
 dracut_args="--add kdumpbase --quiet --hostonly --hostonly-cmdline --hostonly-i18n --hostonly-mode strict -o "plymouth dash resume ifcfg earlykdump""
+compress_args=""
readonly MKDUMPRD_TMPDIR="$(mktemp -d -t mkdumprd.XXXXXX)"
 [ -d "$MKDUMPRD_TMPDIR" ] || perror_exit "dracut: mktemp -p -d -t dracut.XXXXXX failed."
@@ -460,6 +461,9 @@ do
     dracut_args)
         add_dracut_arg $config_val
         ;;
+    compress_args)
+        compress_args="$config_val"
+        ;;
     *)
         ;;
     esac
@@ -480,6 +484,31 @@ if ! is_fadump_capable; then
     add_dracut_arg "--no-hostonly-default-device"
 fi
+if [[ -z $compress_args ]]; then
+    case $(uname -m) in
+        i686|i386|x86_64)
+            compress_args="xz -Xbcj x86"
+            ;;
+        aarch*|armv*)
+            compress_args="xz -Xbcj arm"
+            ;;
+        ppc*)
+            compress_args="xz -Xbcj powerpc"
+            ;;
+        sparc*)
+            compress_args="xz -Xbcj sparc"
+            ;;
+        ia64)
+            compress_args="xz -Xbcj ia64"
+            ;;
+        *)
+            compress_args="xz"
+            ;;
+    esac
+fi
+
+add_dracut_arg "--comp "$compress_args""
+
 echo "$dracut_args $@" | xargs dracut
_rc=$?
-- 
2.30.2

    